From 47d077337a62f3ece41ee90a4d5000876d5c46d1 Mon Sep 17 00:00:00 2001 From: Michael Niedermayer Date: Fri, 10 Jul 2015 18:31:42 +0200 Subject: [PATCH] avcodec/utils: Document 32 min for h264 width Suggested-by: "Ronald S. Bultje" Signed-off-by: Michael Niedermayer --- libavcodec/utils.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/libavcodec/utils.c b/libavcodec/utils.c index 925b3ed047..4245b1a813 100644 --- a/libavcodec/utils.c +++ b/libavcodec/utils.c @@ -432,6 +432,11 @@ void avcodec_align_dimensions2(AVCodecContext *s, int *width, int *height, // some of the optimized chroma MC reads one line too much // which is also done in mpeg decoders with lowres > 0 *height += 2; + + // H.264 uses edge emulation for out of frame motion vectors, for this + // it requires a temporary area large enough to hold a 21x21 block, + // increasing witdth ensure that the temporary area is large enough, + // the next rounded up width is 32 *width = FFMAX(*width, 32); }